The present invention relates in general to data display devices for the visual display of normally encountered conditions such as temperature or pressure which are measured by transducers. The transducers provide a current indication of the condition but do not provide a history of the condition being measured.
In many applications a recording of the history of the condition is important. The prior art has provided numerous devices for recording long term history, for example days, hours or even months. The devices include pen recorders for circular charts for periods from several hours to, usually, a day. Strip chart recorders are provided for recording data over longer term periods. The difference is that the circular chart display all the information while on strip charts the recorded data is rewound onto a takeup roll.
In other cases data is recorded electronically into a device such as a datalogger where it can be retrieved only by electronic devices.
In all such prior art devices the equipment is very expensive and in many cases it is also expensive to maintain.
Additionally because of the nature of the equipment considerable space is required for mounting and servicing the equipment.
No prior art device is known where data can be directly displayed for a period of time which can be easily selected to be adequate for the particular application and easily modified as needed.